Joan Didion on the Céline Ad

When Vogue, a former employer of the esteemed writer Joan Didion, announced on Tuesday that she was starring in Céline’s latest ad campaign, with a photograph featuring her in black shirt, oversize gold pendant and dark sunglasses, the fashion Internet quivered in a way it hasn’t at least since Kim Kardashian stripped nude for Paper magazine two months ago.

Was Ms. Didion aware of the sensation she caused?

“I don’t have any clue,” said the 80-year-old author of well-thumbed classics such as “The White Album,” “Slouching Towards Bethlehem” and “The Year of Magical Thinking,” reached by telephone on Wednesday at her Upper East Side residence (where the photo, by Juergen Teller, was taken). “I have no idea.”

Whose idea was this?

“They got in touch with me,” Ms. Didion said, as crisp as one of Phoebe Philo’s cotton tunics.

Prodded, she added that she is a fan of the brand, which has a store on Madison Avenue near her apartment, and that “I am fortunate enough to own a few” of their things, though she declined to specify which.

She said that she has never been to a Céline show, whose front row recently featured Ms. Kardashian’s husband, Kanye West, but that, “I would love to.”

Fire up the Bombardier, Monsieur Arnault!

Ms. Didion also reminded this reporter that this is not the first time she has acted as a model. Besides the famous cover image of her peering out of her Corvette for her memoir “Where I Was From" — to which Céline paid apparent homage with earlier shots of their usual model, Daria Werbowy — she appeared in a 1989 ad for the Gap.

Correction:

An earlier version of this article misstated the year when Joan Didion’s Gap ad first appeared. It was in 1989, not in 1991.